The present invention relates to the testing of valves, and more particularly, to the acquisition of characteristic data for pneumatic operated valves in the field.
During the past few years, the nuclear power industry has begun to realize the consequence of valve misapplication, improper actuator setup, undersized actuators, and inadequate maintenance. As a result, many operators of nuclear power plants are interested in acquiring database systems by which the base line characteristics of individual valves are stored, and compared with measurements of valve characteristics taken on a periodic basis, whereby deviations from the base line characteristics imply the need for particular maintenance or corrective actions on a valve-by-valve basis. By identifying those valves that need attention well before mis-operation can have an impact on plant safety or performance, the plant operator can safely avoid the overly conservative approach of disassembling and rebuilding every valve on a periodic basis regardless of actual condition.
Known techniques are not well adapted for the accurate determination of the operating characteristic of valve stem displacement as a function of applied air pressure in pneumatic operated valves. More particularly, a pneumatic valve, which operates in a relatively straight-forward, uncomplicated manner, should be amenable to an inexpensive, easily implemented technique for acquiring stem displacement data.